This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A169935 #7 Jun 16 2013 10:39:06 %S A169935 1,2,3,4,5,6,7,8,9,11,12,16,17,22,23,27,28,33,34,38,39,40,44,45,49,50, %T A169935 51,55,56,61,62,66,67,72,73,77,78,83,84,88,89,90,94,95,99,111,112,116, %U A169935 117,222,223,227,228,333,334,338,339,440,444,445,449 %N A169935 Numbers n such that for some k>0, n*k=1 in the arithmetic defined in A169918. %C A169935 These would be the units if the structure formed a ring (which it does not). %e A169935 22 is a member since 22*88 = 1. So is 23 since 23*8 = 1. 10 is not a member, even though 10 divides 9, since 10*9 = 0. %K A169935 nonn,base %O A169935 1,2 %A A169935 _David Applegate_, _Marc LeBrun_ and _N. J. A. Sloane_, Jul 21 2010